Sheet materials such as loose leaf sheets of paper and similar thin stackable materials can be organized and kept in binders of many types. Some binder systems include so-called “three-ring binder” systems consisting of a central spine or hinge apparatus having a plurality (e.g., three) articulated split rings that thread into corresponding holes punched into an edge of the papers to be bound, then the binder rings are snapped shut to form a closed ring shape enclosing and securing the punched papers. Other systems include a pinching mechanism that applies mechanical frictional force to pinch a plurality of sheets between two sides of a clamp. Still other types of binders, sometimes called “spiral notebooks”, require drilling many small holes into an edge of the sheets, and then a metal or plastic spiral element is threaded into the small holes all along the drilled edge of the sheets to form a notebook of said sheets. Soft or hard covers can be added to either side of the stack of bound sheets for protection of the sheets against wear and tear.
Most existing binder systems require physical marking or punching or drilling or perforating of the bound sheets such as in the case of three-ring binders. Additionally, most existing notebook systems do not allow a user to configure the contents or their order such as in the case of spiral notebooks systems. Some clamping type binders exist but these are generally too bulky, have non-ideal clamp geometries, and are not flexible for multiple types of use. Other pinching type systems are not mechanically robust and are only suitable for light-weight temporary report formats for a limited number of sheets.
FIG. 1 illustrates a clasp style paper binding system which can be used to secure a few thin sheets such as a few sheets of paper in a report, memo or similar document. The binder consists of substantially an elongated clasp 100 typically made of bendable polymer material such as a hard plastic. The clasp 100 includes a C-shaped cross section having a closed end 102 and an opposing openable end 104. One or more thin sheet stock material 110 can be inserted at a first edge 112 thereof into the clasp 100 through the openable end 104. Thin sheets 110 are secured on one edge thereof referred to as a bound edge 112, and an opposing unbound edge 114 allows a user to flip through the one or more sheets 110. Such clasp style binders are relatively inexpensive and compact, yet they are only suitable for a small number of sheets 110 and cannot withstand excessive mechanical force or stress as this would damage or open clasp 100 causing the sheets to be discharged therefrom and become lost or damaged. Furthermore, this type of binder is limited by the material construction and dimensions of clasp 100, which is usually a thin plastic material and only suitable for basic applications such as containing a few sheets of a report or a memo or other short documents.
FIG. 2 illustrates another type of paper binding according to the prior art. Spring-action binder 200 includes a pair of openable cover panels 202 made of a relatively rigid material such as strong cardboard. The cardboard sides are bound to a spring-loaded tubular spine 210. The tubular spine 210 has a closed rounded back 211 and a pinched openable mouth 212 when viewed in cross section and defines an air gap 214 within the tubular spine 210.
The spring-action binder 200 is operated by spreading apart the two cover panels 202. This causes the spring-loaded spine 210 to expand in cross section at its pinched openable portion 212, which can be pried apart to accommodate a plurality of sheets that are subsequently pinched to secure them in the binder 200.
Binder 200 designs suffer from the bulky design of the spring-loaded tubular spine members 210, especially when coupled with conventional binder cover materials 202. The cross-sectional size of binder spine 210 is larger than desired for most personal use applications, which causes the binder to be about one inch or more in girth no matter how few sheets are secured therein. Also, the curved back 102 of binder spine 100 of FIG. 1 and the curved back 211 of binder spine 210 of FIG. 2 are not conducive to placement of the binder on its back when in an open configuration during use. So these binder types are not convenient for users to open and write or read the contents thereof such as a user might do with an ordinary hard-covered book. The binders of FIG. 2 tend to flop around on their backs from side to side, or rock from side to side when opened and placed on a flat surface such as a table top. Additionally, binder 200 is not conducive to annotations to be made on the exterior of its spine 210 because this spine has a rounded profile 211. Finally, such binders are not ideally suited for archiving on a shelf in a series of continuous binders of this sort, as their bindings 210 do not sit uniformly side by side in a tidy manner, and have different appearance from one to the next depending on the number of sheets placed into binder 200.
An additional challenge with existing sheet binder designs is that they are commonly awkward to hold open and generally do not stay open due to natural inward (closing) resistance by the binding members thereof. Improved designs to overcome some or all of the foregoing challenges are desired.